This invention relates to novel copolymerizable phenolic antioxidants, copolyetheresters stabilized with said antioxidants, and a method for preparing such stabilized copolyetheresters.
Copolyetheresters undergo degradation upon being exposed to air at elevated temperatures due to oxidative and thermal decomposition of the polymer. This severely limits the use of copolyetheresters for many applications unless they are stabilized against degradation. A multitude of stabilizers that impart oxidative stability to copolyetheresters have been suggested. However, most stabilizers used have not been entirely satisfactory and many have rather serious defects. For example, there are two primary classes of antioxidants used for stabilzing copolyetheresters: arylamine antioxidants and hindered phenols. Arylamine antioxidants cause severe staining of materials in contact with the stabilized copolyetherester. Hindered phenolic stabilizers have been used with more success, but at concentrations where they provide reasonable protection, they often exceed their solubility limit, migrate to the surface and form unsightly bloom. Arylamine antioxidants and hindered phenols can be leached from the polymer or volatilized which, of course, in either event, results in loss of effectiveness of the stabilizer. Thus, there is a need for stabilizers that effectively prevent oxidative decomposition of copolyetheresters, without the problems of prior art stabilizers.